That was a great video Ian, but I've found an image of the Milk Hill Galaxy formation that's large enough to see most of the flaws:
http://circularstateofmind.files.wordpress.com/2012/08/galaxy1.jpg
If you further enlarge the image, you'll be able to see the curved connecting paths in all six arms.
In addition, some of the little satellite circles (I think Williams calls them fractals) are badly spaced. The two most glaring errors of this nature pertain to the arms originating at approximately the 11:00 and 7:00 positions in relation to the center circle. If you start with the 11:00 arm and follow the small circles to the right of the arm, you'll see a large gap between the seventh and eighth arm circles. The error occurs at the same position in the 7:00 arm, although it's not as large. If you look closely at the other arms, you'll see even more satellite placement errors.
Finally, there are stomp marks in the larger circles, although they're hard to see because most of the images are too small to make them out. Fortunately, this video has some great closeups (starting at ~1:45) that clearly show them.
The Giant Milk Hill Spiral Crop Circle Formation
Doug